Apparatus and method for measuring an anatomical angle of a body

ABSTRACT

An apparatus (20) for automatically measuring an anatomical angle of a body, the apparatus (20) comprising aligning means (23) for aligning an axis (22) of the apparatus (20) with anatomical landmarks of the body, sensing means (30) for sensing an orientation of the axis (22) while the axis is aligned with the landmarks, and processing means (40) for processing the sensed orientation. The sensing means (30) comprises a magnetometer (32) and an accelerometer (31), and the aligning means comprises a pair of lasers.

FIELD OF THE INVENTION

The present invention relates generally to an apparatus and method formeasuring an anatomical angle of a body.

Although the present invention will be described with particularreference to measuring an anatomical angle of a human body, it willnevertheless be appreciated that the invention is not necessarilylimited to this use.

BACKGROUND ART

Goniometers are apparatus which are used by physiotherapists and thelike to measure anatomical angles of a body. For example, they are oftenused to measure the range of angular motion of joints.

The following patent documents disclose examples of known goniometers aswell as other apparatus for measuring angles: U.S. Pat. No. 4,771,548(Donnery), United States Patent Application Publication No. 2006/0137201A1 (Dixon, et al.), U.S. Pat. No. 6,469,666 (Tonn), U.S. Pat. No.7,337,751 (Lopez, et al.), U.S. Pat. No. 4,442,606 (Graham, et al.),U.S. Pat. No. 7,204,030 Matter), U.S. Pat. No. 7,293,363 (Emmett L.Parker), United States Patent Application Publication No. 2007/0266579A1 (Briscoe, et al.), U.S. Pat. No. 5,163,228 (Edwards, et al.). U.S.Pat. No. 4,665,928 (Linial, et al.), U.S. Pat. No. 3,879,136 (Takeda),U.S. Pat. No. 4,665,928 (Linial, et al.), United States PatentApplication Publication No. 2003/0226268 A1 (Gibson), U.S. Pat. No.7,359,750 (Song, et al.), U.S. Pat. No. 5,253,655 (Stone, et al.), andInternational Patent Application No. PCT/DE1993/000891.

Many existing goniometers include a pair of aligning arms which are ableto pivot relative to each other. In use, each arm is aligned withanatomical landmarks which are adjacent to the body part whose angle isbeing measured. For example, if a goniometer with arms is used tomeasure the angle between the upper part of a person's leg and the lowerpart of their leg, one of the arms of the goniometer will be alignedwith landmarks on the upper part of the leg while the other arm isaligned with landmarks on the lower part of the leg. Once the arms havebeen properly aligned with the upper and lower leg parts, the anglebetween the arms corresponds to the angle between the leg parts and canbe read off an analogue scale of the goniometer.

Goniometers of the above-described type suffer from the disadvantagethat the arms are often not long enough to accurately align them withsome anatomical landmarks. When this situation arises, the person usingthe goniometer will usually use an eye-balling approach to align thearms with the landmarks as best they can. The accuracy of themeasurement which is obtained will be reduced if the arms are notproperly aligned with the landmarks.

Although this problem can be overcome by extending the length of thearms (e.g. by making the arms extendable) so that they are able to reachall of the landmarks that they need to be aligned with when making ameasurement, doing so would make the arms somewhat of an obstruction toa user and also make them more vulnerable to being broken or bent.

Measurement inaccuracy can also be introduced by the analogue scale ofthe goniometer from which the angle measurement is read. This is becausethe user needs to interpret the reading from the scale. Although somedevices include a digital display which can address this problem, thedisplays tend to be small and difficult to read.

For various reasons, including those given above, many existinggoniometers have poor inter therapist reliability because thevariability of readings from one user to another tends to besignificant. For example, there can be a 5-10 degree variance betweendifferent users. Similarly, many existing goniometers have poor intratherapist reliability because the variability of readings from the sameuser tends to be significant. As a consequence, measurements obtainedfrom such goniometers are generally not taken seriously.

The inaccuracy and variance of readings obtained from existinggoniometers can have significant negative consequences. For example, ifa post-operative patient who has had a joint operated on must gain acertain amount of range of motion in that joint before they are able tobe discharged from hospital, and if a therapist uses a goniometer tomeasure the range of motion of the joint to determine whether or not thepatient has gained the required amount of motion, the date on which thepatient is discharged will be unnecessarily delayed if the patient doeshave the required range of motion but, due to an inaccurate measurementobtained from the goniometer, the measured range indicates that they donot have the required range. An unnecessary delay in the patient beingdischarged means that the patient will needlessly be occupying ahospital bed which should be made available to someone else.

Another problem with many existing goniometers is that a user oftenneeds to operate them with both of their hands. This means that whilethey are performing a measurement with such a device they do not have ahand available to assist the person on whom they are performing themeasurement, or to write down the measurement which is obtained from thedevice.

Furthermore, many existing goniometers (particularly those which havealigning arms) are quite bulky. This bulkiness can contribute to theneed for users to operate them with both hands.

Existing goniometers which have short aligning arms and/or analoguescales can also be time-consuming to use, particularly if an accuratemeasurement is required. This is because it can take time to properlyalign the arms with landmarks that the arms cannot reach, and because itcan take time to properly read the scale.

In addition, at present, different sized goniometers are required toobtain measurements of different sized joints. A large goniometer isrequired in order to take measurements for the hip and other largejoints. A small goniometer is required in order to take measurements ofmedium size joints and also to take measurements on the pediatricpopulation. A finger joint goniometer is required in order to measurethe angle of finger joints.

It is against this background that the present invention has beendeveloped.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome, or at leastameliorate, one or more of the deficiencies of the prior art mentionedabove, or to provide the consumer with a useful or commercial choice.

Other objects and advantages of the present invention will becomeapparent from the following description, taken in connection with theaccompanying drawings, wherein, by way of illustration and example, apreferred embodiment of the present invention is disclosed.

According to a first broad aspect of the present invention, there isprovided an apparatus for measuring an anatomical angle of a body, theapparatus comprising aligning means for aligning an axis of theapparatus with anatomical landmarks of the body, sensing means forsensing an orientation of the axis while the axis is aligned with thelandmarks, and processing means for processing the sensed orientation.

In one preferred embodiment, the processing means is able to process asensed first orientation of the axis and a sensed second orientation ofthe axis to determine an angle between the axis in the sensed firstorientation and the axis in the sensed second orientation. Preferably,the apparatus also comprises another aligning means for aligning theaxis with anatomical landmarks of the body. Preferably, the sensingmeans includes a tilt sensor for sensing the tilt of the axis, and amagnetic sensor for sensing the direction of the axis relative to amagnetic field. Preferably, the tilt sensor is able to sense the pitchand roll of the axis. It is preferred that the tilt sensor is anaccelerometer. It is also preferred that the magnetic sensor is amagnetometer.

In another preferred embodiment, the apparatus also comprises anotheraligning means for aligning another axis of the apparatus with otheranatomical landmarks of the body, the aligning means are able to bepivoted relative to each other so as to vary an angle between the axes,and the processing means is able to process the sensed orientation todetermine the angle between the axes.

Preferably, each aligning means is a light source. It is preferred thatthe light source is a focused or collimated light source. It isparticularly preferred that the light source is a laser. For example,the laser may be a solid-state laser.

Preferably, the processing means is a microprocessor.

Preferably, the apparatus also comprises a display for displaying themeasured angle. It is preferred that the display is a liquid-crystaldisplay (LCD). It is also preferred that the measured angle is displayedin units of degrees.

Preferably, the apparatus also comprises at least one switch forallowing a user to control the operation of the apparatus. It ispreferred that the switch is a pushbutton switch.

Preferably, the apparatus also comprises storage means for storinginstructions or data for processing by the processing means. It ispreferred that the storage means is a non-volatile memory.

Preferably, the apparatus is able to be powered by a battery. It ispreferred that the apparatus is able to be powered by a lithium battery.

It is preferred that the apparatus also comprises a charger for chargingthe battery. The charger is preferably a Universal Serial Bus (USB)charger.

Preferably, the apparatus also comprises a housing for housing thealigning means, sensing means and processing means.

According to a second broad aspect of the present invention, there isprovided a method for measuring en anatomical angle of a body, themethod comprising the steps of:

aligning an axis with anatomical landmarks of the body;

sensing an orientation of the axis while the axis is aligned with thelandmarks; and

processing the sensed orientation.

In one preferred embodiment, the sensing step includes sensing a firstorientation of the axis and sensing a second orientation of the axis,and the processing step includes processing the first sensed orientationand the second sensed orientation to determine an angle between the axisin the sensed first orientation and the axis in the sensed secondorientation. Preferably, each orientation is sensed by sensing the tiltof the axis and the direction of the axis relative to a magnetic field.It is preferred that the tilt of the axis is sensed by sensing the pitchand roll of the axis.

In another preferred embodiment, the method also comprises the step ofaligning another axis with other anatomical landmarks of the body byvarying an angle between the axes, and the processing step includesprocessing the sensed orientation to determine the angle between theaxes.

Preferably, each aligning step includes aligning a light beam with thelandmarks. It is preferred that the light beam is a collimated lightbeam. It is particularly preferred that the light beam is a laser beam.

Preferably, the method also comprises the step of displaying themeasured angle.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the invention may be more fully understood and put intopractice, a preferred embodiment thereof will now be described withreference to the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of an apparatus according to a firstpreferred embodiment of the present invention when a battery forpowering the apparatus is being charged from an external supply ofelectricity;

FIG. 2 is a front perspective view of the apparatus according to thefirst preferred embodiment of the present invention;

FIG. 3 is a rear elevation of the apparatus illustrated in FIG. 2;

FIG. 4 depicts the printed circuit board and display of the apparatusillustrated in FIG. 2 after pressing both switches of the apparatus;

FIG. 5 depicts the printed circuit board and display after both switchesare pressed again;

FIG. 6 depicts the printed circuit board and display after rotating theapparatus and then pressing both switches again;

FIG. 7 depicts the printed circuit board and display after againpressing both switches;

FIG. 8 is a flowchart of a method of operating the apparatus illustratedin FIGS. 1 to 7;

FIG. 9 depicts an apparatus according to a second preferred embodimentof the present invention being used to measure an anatomical angle at aperson's knee joint;

FIG. 10 depicts an apparatus according to a third preferred embodimentof the present invention when the lasers of the apparatus are activated;

FIG. 11 depicts the three main steps in operating the apparatusillustrated in FIG. 10 to measure an anatomical angle at a person's kneejoint;

FIG. 12 is a schematic block diagram of an apparatus according to afourth preferred embodiment of the present invention;

FIG. 13A is a front elevation of the apparatus according to the fourthpreferred embodiment of the present invention; and

FIG. 13B is a flowchart of a method of operating the apparatusillustrated in FIGS. 12 and 13.

BEST MODE(S) FOR CARRYING OUT THE INVENTION

In the figures, like features of the described preferred embodiments ofthe present invention have been referenced with like reference numerals.

Referring to FIGS. 1 to 4, there is depicted an apparatus 20 accordingto a first preferred embodiment of the present invention. Apparatus 20is for measuring an anatomical angle of a body such as a human body.Apparatus which are used for this purpose are usually referred to asgoniometers by physiotherapists and the like.

Apparatus 20 includes a pair of aligning or alignment means that areeach in the form of a solid-state laser 23. Lasers 23, which arediametrically opposite each other, are for aligning an axis 22 of theapparatus 20 with anatomical landmarks of a body. Each Laser 23 is ableto emit a respective focused or collimated light beam in the form of alaser beam. The lasers 23 emit the laser beams outwardly from theapparatus 20 such that the laser beams are co-linear with each other andthe axis 22 of the apparatus 20. Lasers 23 are preferably low-powerlasers so that they do not pose a health risk.

A sensing means 30 of the apparatus 20 is a three-dimensionalorientation sensor which is able to sense a first orientation of theapparatus 20 and, hence, the axis 22 in three dimensions, while the axis22 is aligned with first anatomical landmarks of the body, and is alsoable to sense a second orientation of the apparatus 20 and, hence, theaxis 22 in three dimensions, while the axis 22 is aligned with secondanatomical landmarks of the body. Sensing means 30 includes a tiltsensor which is in the form of an accelerometer 31, and a magneticsensor which is in the form of a magnetometer 32. Sensing means 30 isable to provide stable measurement/sensing of the three-dimensionalorientation of an object in space, regardless of the object'sorientation.

Accelerometer 31 is able to sense the tilt of the apparatus 20 and,hence, the axis 22. In particular, accelerometer 31 is able to sense thepitch (i.e. up/down position) and roll (i.e. side to side rockingposition) of the apparatus 20 and, hence, the axis 22.

Magnetometer 32 is able to sense the yaw (rotational position about avertical axis) of the apparatus 20 and, hence, the axis 22 relative to amagnetic field such as the earth's magnetic field.

The three-dimensional orientation of the apparatus 20 and axis 22,including the pitch, roll and yaw of the apparatus 20 and axis 22, whichis sensed by the sensing means 30 is able to be output by the sensingmeans 30 to a processing means which is in the form of a microprocessor40. The sensed three-dimensional orientation is output by the sensingmeans 30 in the form of three-dimensional coordinates. In addition tothe accelerometer 31 and magnetometer 32, sensing means 30 includesinterfacing circuitry (not depicted) for interfacing the accelerometer31 and the magnetometer 32 with the microprocessor. Microprocessor 40 isable to determine an angle between the axis 22 in the sensed firstorientation and the axis 22 in the sensed second orientation byprocessing the output of the sensing means 30 in accordance withcomputer-readable instructions which are able to be read by themicroprocessor 40 and which are stored on storage means which is in theform of a non-volatile memory 41. Microprocessor 40 is able to outputthe determined angle to a liquid-crystal display (LCD) 42 which is thenable to display the angle numerically in units of degrees. LCD 42 has aheight of 32.41 mm, and a width of 61.82 mm.

Suitably pressing a pair of pushbutton switches 43 enables a user tocontrol the operation of the microprocessor 40 and, hence, the apparatus20.

Apparatus 20 is powered by a battery 44. The battery 44 may for examplebe a long-life lithium battery. The battery 44 can be charged by abattery charger such as a Universal Serial Bus (USB) charger 45 which isconnected to an external charging supply of electricity 46.

Lasers 23, sensing means 30 including the accelerometer 31 andmagnetometer 32, microprocessor 40, non-volatile memory 41, LCD 42, andswitches 43 are all mounted on a printed circuit board (PCB) 47. PCB 47is generally circular and has a radius of curvature of 30 mm. PCB 47includes a pair of diametrically opposite recesses 48 for receiving thelasers 23. A respective pair of contact prongs 49 is secured to the PCB47 and extends into each recess 48 from the PCB 47. Each pair of contactprongs 49 plugs into a respective slot (not depicted) in a socket (notdepicted) of each laser 23.

PCB 47 is housed within a hollow disc-shaped housing 51. Housing 51includes an opening or window 52 through which the measured angle whichis displayed by LCD 42 can be viewed. It also includes a pair of buttons53 which are located on diametrically opposite sides of the housing 51.Each button 53 operatively engages with a respective switch 43 such thatthe switch 43 is able to be operated by pressing the button 53. Eachlaser 23 is located in the housing 51 such that the lasers 23 do notprotrude from the housing 51. Also, each laser 23 is located adjacent toa respective recess 54 in the housing 51 such that the housing 51 doesnot obstruct the laser beams which are emitted by the lasers 23.

With reference to FIGS. 4 to 7, and FIG. 8 which depicts a flowchart ofa method 60 of operating the apparatus 20, the apparatus 20 may be usedto measure an anatomical angle of a body joint by firstly performing anactivation step 61. The activation step 61 involves a user pressing bothbuttons 53 simultaneously with to activate (i.e. turn on) the apparatus20. Once the buttons 53 have been pressed, both of the lasers 23 emit alaser beam, and the LCD 42 displays a numeric value in the range of0-180 degrees. The value which is displayed by the LCD 42 depends on theorientation of the apparatus 20 and axis 22 at the time, and will changedynamically in response to a change in the orientation of the apparatus20 and axis 22. FIG. 4 depicts the LCD 42 displaying a value of 20.0degrees shortly after activation of the apparatus 20.

The next step of the method 60 is step 62 which is to align the laserbeams which are emitted by the lasers 23 with first anatomical landmarksof the body which the joint forms part of. The laser beams are alignedwith the first anatomical landmarks such that each laser beam intersectsa respective one of the first anatomical landmarks. If the apparatus 20is being used to measure a range of angular motion of a joint of a limb,the laser beams are initially aligned with landmarks at a distal end orpart of the limb i.e. below the joint. For example, when measuringshoulder flexion when the patient is in supine, the apparatus 20 ispositioned so that the laser beams align with the landmarks of thegreater trochanter of the hip, along the line of the trunk to the midaxilla.

The landmarks which the laser beams are aligned with may be non jointlandmarks and/or joint landmarks (e.g. landmarks indicating the axis ofa joint). The particular landmarks which are used by physiotherapistsand the like to measure anatomical angles are well-known in the art andwill not be described at length here.

Step 63, which follows step 62, involves sensing a first orientation ofthe apparatus 20 and axis 22 with the sensing means 30, and thencapturing that information with the microprocessor 40. The firstorientation of the apparatus 20 and axis 22 is the orientation that theapparatus 20 and axis 22 have when the laser beams emitted by the lasers23 are aligned with the first anatomical landmarks of the body. Pressingboth buttons 53 simultaneously while the laser beams emitted by thelasers 23 are aligned with the first anatomical landmarks causes thefirst orientation which is sensed by the sensing means 30 to be capturedby the microprocessor 40.

Following step 63, the apparatus 20 automatically performs step 64 whichis to zero the numeric value which is displayed by the LCD 42 so thatthe LCD will display a value of 0.0 degrees while the apparatus 20 andaxis 22 are in the first orientation. FIG. 5 depicts the LCD 42displaying a value of 0.0 degrees after the first orientation of theapparatus 20 and axis 22 have been detected, and after the numeric valuedisplayed by the LCD 42 has been zeroed.

In other embodiments, the numeric value which is displayed by the LCD 42may be set to zero at the time that the apparatus 20 is activated.

The next step of the method 60 is step 65 which is to align the laserbeams which are emitted by the lasers 23 with second anatomicallandmarks of the body which the joint forms part of. The laser beams arealigned with the second anatomical landmarks such that each laser beamintersects a respective one of the second anatomical landmarks. If theapparatus 20 is being used to measure a range of angular motion of ajoint of a limb, the laser beams are aligned with landmarks at aproximal end or part of the limb (i.e. above the joint) after movementof the joint. For example, when measuring shoulder flexion, theapparatus 20 is positioned so that the laser beams align with thelandmarks of the mid axilla to the medial epicondyle on the humerus.

Step 66, which follows step 63 involves sensing a second orientation ofthe apparatus 20 and axis 22, and capturing that information. The secondorientation of the apparatus 20 and axis 22 is the orientation that theapparatus and axis 22 have when the laser beams emitted by the lasers 23are aligned with the second anatomical landmarks of the body. Pressingboth buttons simultaneously while the laser beams emitted by the lasers23 are aligned with the second anatomical landmarks causes the secondorientation to be captured from the sensing means 30 by themicroprocessor 40.

Step 67 of the method 60 occurs automatically after step 66. In step 67,the microprocessor 40 processes the sensed first orientation and thesensed second orientation to determine what the measured anatomicalangle of the joint is.

The sensed first orientation includes a vector A (i.e. Axyz) which is aninitial reference position. Vector A is sensed by the magnetometer 32,and includes pitch and roll angles which are sensed by the accelerometer31. The sensed second orientation includes a vector B (i.e. Bxyz) whichis a final reference position. Vector B is sensed by the magnetometer32, and includes pitch and roll angles for vector B which are sensed bythe accelerometer 31. Microprocessor 40 processes the sensed firstorientation and the sensed second orientation by transposing vector Aand Vector B to the horizontal plane so that vector A (i.e. Axyz)becomes vector A′xy, and so that vector B (i.e. Bxyz) becomes vectorB′xy. The microprocessor 40 then determines the angle between transposedvector A′xy and transposed vector B′xy, and this is the angle which isdisplayed by the LCD 42 at step 68. A similar method is used by acompass system disclosed in a published article which is entitled“Applications of Magnetic Sensors for Low Cost Compass Systems”, byMichal J. Caruso of Honeywell, SSEC, and which is incorporated herein itits entirety by reference.

After determining the anatomical angle of the joint, the next step whichis performed is step 68 which involves the microprocessor 40 controllingthe LCD 42 to display this information numerically and in units ofdegrees. The measured anatomical angle is displayed to an accuracy of asingle decimal place. This information remains display by the LCD 42irrespective of whether or not the apparatus 20 is subsequently moved.In addition, the lasers 23 are turned off so that they no longer emitlaser beams. FIG. 6 depicts the LCD 42 displaying a measured angle of65.0 degrees.

The next step in the method is step 69 which involves the user pressingboth buttons 53 so that the apparatus 20 is deactivated (i.e. turnedoff). FIG. 7 depicts the blank display 42 of the apparatus 20 after ithas been turned off.

It will be appreciated that the sensing means 30 is not limited toincluding the accelerometer 31 and magnetometer 32 to sense theorientation of the axis 22 in three-dimensions, and that the sensingmeans 30 could use other devices/instruments to sense thethree-dimensional orientation of the axis 22. For example, the sensingmeans 30 could use electrolytic (fluid) based tilt sensors, gimbaledmechanical structures, gyroscopes, magnetic compasses to sense theorientation of the axis 22.

The apparatus 20 may be used to measure the anatomical angle of smalljoints (e.g. finger joints) or the small joints of infants and the likein pediatric settings by selecting a small joint mode of operation ofthe apparatus by suitably pressing the buttons 53. In the small jointmode, only one of the lasers 23 is activated.

Referring to FIG. 9, an apparatus 80 according to a second preferredembodiment of the present invention is being used by a user 81 tomeasure an anatomical angle of a patient's right knee joint 82. Apartfrom some minor cosmetic differences, apparatus 80 is identical to theapparatus 20. User 81 is shown aligning laser beams 83 which are emittedby the lasers (not depicted) of the apparatus 80 with anatomicallandmarks 84, 85 of the patient's right leg 86 while holding theapparatus 80 in their right hand 87 adjacent to the patient's lowerright leg 88. The apparatus 80 is initially placed on the anatomicalbone of the lower right leg 88 to allow intersection of the laser beams83 with the knee joint 82 and the proximal landmark 84 of the knee 82.Laser beams 83 are co-linear with an axis 22 of the apparatus 80.

FIG. 10 depicts an apparatus 90 according to a third preferredembodiment of the present invention which is also identical to theapparatus 20 apart from some minor cosmetic differences. The lasers 23of the apparatus 90 are shown emitting laser beams 83, and the LCD 42 ofthe apparatus 90 is shown displaying an angular reading of 126.0degrees. A degrees symbol ‘°’ is displayed on the LCD 42 at theright-side of the angular reading to make it clear to a person readingthe LCD 42 that the angular reading displayed thereon is in units ofdegrees. Laser beams 83 are co-linear with an axis 22 of the apparatus90.

FIG. 11 depicts the three main steps in operating the apparatus 90 tomeasure an anatomical angle at a person's knee joint. Those steps are:

1. Activate;

2. Calibrate; and

3. Calculate.

In the Activate step, the apparatus 90 is activated (i.e. turned on) bypressing the buttons 53. When the apparatus 90 is activated, the LCD 42and the lasers 23 are activated.

In the Calibrate step, the laser beams 83 are aligned with landmarks ofthe lower part of the leg, and then buttons 53 are pressed again to zerothe reading which is displayed by the LCD 42.

In the Calculate step, the laser beams 83 are aligned with landmarks ofthe upper part of the leg, and then buttons 53 are pressed again so thatthe apparatus 90 calculates the angle between the laser beams 83 whenthey are aligned with the landmarks of the lower part of the leg and thelaser beams 83 when they are aligned with the landmarks of the upperpart of the leg.

If a user holds down the two buttons 53 for at least 5 seconds, a menu(not depicted) is displayed by the LCD 42. The menu includes a heading“Instructions for application 1, 2, 3 use”, and includes the followingitems:

1, Landmark review

2. Small joint mode

The menu items can be scrolled through by pressing the buttons 53. Toscroll up through the menu items, the topmost button 53 is pressed. Toscroll down through the menu items, the bottommost button 53 is pressed.To select a menu item, the both buttons 53 are held down for at least 5seconds.

Selecting menu item 1—Landmark review causes a submenu to be displayedby the LCD 42. The submenu includes a list of joints (e.g. shoulder,elbow, wrist, etc.) which can be measured and whose angular measurementscan be reviewed.

Selecting menu item 2—Small joint mode results in only one of the lasers23 being activated. This means that the lasers 23 can work independentlyof each other. Small joint mode is used when measuring an anatomicalangle of a small joint. When measuring an anatomical angle of a smalljoint (e.g. a finger joint), both lasers 23 are unable to be used in themanner described previously because the apparatus 90 is too large andwould cover the landmarks which the laser beams 83 need to be alignedwith. In the small joint mode, only one of the lasers 23 is activated,and the laser beam 83 which it emits Is aligned with the landmarks.

Referring to FIGS. 12 and 13, there is depicted an apparatus 100according to a fourth preferred embodiment of the present invention.Apparatus 100 is for measuring an anatomical angle of a body such as ahuman body. Apparatus which are used for this purpose are usuallyreferred to as goniometers by physiotherapists and the like.

Apparatus 100 includes an aligning or alignment means that are each inthe form of a solid-state laser 23. Lasers 23 are for aligning a firstaxis 101 of the apparatus 100 with first anatomical landmarks of a humanbody, and for aligning a second axis 22 of the apparatus 100 with secondanatomical landmarks of the body. Lasers 23 are each able to emit arespective focused or collimated light beam in the form of a laser beam83. The lasers 23 emit the laser beams 83 outwardly from the apparatus100 such that one of the laser beams 83 is co-linear with the first axis101, and such that the other laser beam 83 is co-linear with the secondaxis 22. Lasers 23 are preferably low-power lasers so that they do notpose a health risk.

Apparatus 100 also includes a hollow disc-shaped housing 51 which isapproximately 50 mm in diameter and which includes an inner circularpart 102 which one of the lasers 23 is fixed relative to, and an outercircular part 103 which the other laser 23 is fixed relative to. Theouter part 103 is able to rotate relative to the inner part 102 ineither a clockwise or an anticlockwise direction as indicated by thearrow ‘A’ in FIG. 13. The laser 23 which is fixed relative to the innerpart 102 is the laser 23 which is for aligning the first axis 101 withfirst anatomical landmarks of the body, and the laser 23 which is fixedrelative to the outer part 103 is the laser 23 which is for aligning thesecond axis 22 with second anatomical landmarks of the body. The anglebetween the lasers 23 and, hence, the axes 22 and 101 can be varied byrotating the outer part 103 relative to the inner part 102. The outerpart 103 can be rotated relative to the inner part through 360 degrees.

A sensing means 30 of the apparatus 100 is able to sense an orientationof the second axis 22 relative to the first axis 101. In particular,sensing means 30 is able to determine the angular orientation of thesecond axis 22 relative to the first axis 101.

The sensed orientation is able to be output by the sensing means 30 to aprocessing means 40 which is in the form of a microprocessor 40.

Microprocessor 40 is able to determine the angle between the first axis101 and the second axis 22 by processing the sensed orientation which isoutput by the sensing means 30 in accordance with computer-readableInstructions which are able to be read by the microprocessor 40 andwhich are stored on storage means which is in the form of a non-volatilememory 41. Microprocessor 40 is able to output the determined angle to aliquid-crystal display (LCD) 42 which is then able to display the anglenumerically in units of degrees. The angle is displayed to the nearestdegree. LCD 42 can display a maximum angle of 360 degrees and a minimumangle of 0 degrees.

A pushbutton switch 43 enables a user to control the operation of themicroprocessor 40 and, hence, the apparatus 100.

Apparatus 100 is powered by a battery 44. The battery 44 may for examplebe a long-life lithium battery. The battery 44 can be charged by abattery charger such as a Universal Serial Bus (USB) charger 45 which isconnected to an external charging supply of electricity 46.

Lasers 23, sensing means 30, microprocessor 40, non-volatile memory 41,LCD 42, and switch 43 are all housed within the housing 51. Housing 51includes an opening or window 52 through which the measured angle whichis displayed by LCD 42 can be viewed. It also includes a button 53 whichis located on the front of the housing 51 adjacent to the LCD 42. Button53 operatively engages with the switch 43 of the apparatus 100 such thatthe switch 43 is able to be operated by pressing the button 53.Although, for clarity, the lasers 23 are shown protruding from thehousing 51, they may alternatively be located in the housing 51 suchthat they do not protrude from the housing 51 and such that the housing51 does not obstruct the laser beams 83 which are emitted by the lasers23.

With reference to FIGS. 12 and 13, and also FIG. 14 which depicts aflowchart of a method 120 of operating the apparatus 100, the apparatus100 may be used to measure an anatomical angle of a body joint byfirstly performing an activation step 121. The activation step 121involves a user pressing the button 53 to activate (i.e. turn on) theapparatus 100. Once the button 53 has been pressed, the lasers 23 emitlaser beams 83, and the LCD 42 displays a numeric value in the range of0-360 degrees. The value which is displayed by the LCD 42 depends on theorientation of the axis 22 relative to the axis 101 at the time, andwill change dynamically if the orientation of the axis 22 relative tothe axis 101 is altered by rotating the outer part 103 of the housing 51relative to the inner part 102 of the housing. Rotating the outer part103 relative to the inner part 102 changes the orientation of the axis22 relative to the axis 101 by changing the angle between the axes 22,101.

The next step of the method 120 is step 122 which is to position thehousing 51 over the joint so that the laser beams 83 can be aligned withpredetermined anatomical landmarks which are located above and below thejoint.

At step 123 the laser beam 83 which is co-linear with the first axis 101is aligned with first anatomical landmarks. The laser beam 83 is alignedwith the first anatomical landmarks such that the laser beam 83intersects each one of the first anatomical landmarks.

At step 124, the laser beam 83 which is co-linear with the second axis22 is aligned with second anatomical landmarks. The laser beam 83 isaligned with the second anatomical landmarks such that the laser beam 83intersects each one of the second anatomical landmarks.

Aligning the laser beams 83 with the first and second anatomicallandmarks may require adjustment of the angle between the axes 22, 101by suitably rotating the outer part 103 of the housing 51 relative tothe inner part 102 of the housing 51.

At step 125, the sensing means 30 senses the orientation of the secondaxis 22 relative to the first axis 101 while those axes 22, 101 arealigned with the second and first anatomical landmarks, respectively. Atstep 126, the microprocessor 40 processes the sensed orientation todetermine the angle between the first axis 101 and the second axis 22and controls the LCD 42 to display the angle between the first axis 101and the second axis 22.

At step 128, the apparatus 100 is deactivated (i.e. turned off) bypressing the button 53.

By employing lasers 23 instead of arms or the like as aligning meansassists to make the apparatus described above more compact compared toexisting goniometers which have long arms for alignment purposes.

The various apparatus described above may be used to measure the rangeof motion of an anatomical joint.

A user may operate the various apparatus described above using only oneof their hands. This enables the user to use their free hand to assist apatient if need be, or to record the angular measurement which isobtained using the apparatus.

The lasers 23 allow the various axes of the apparatus described above tobe accurately aligned with anatomical landmarks. This together with theautomatic and accurate sensing, processing and display of theorientation of the various axes enables the apparatus to provide anaccurate angular measurement which is more likely to be replicatedbetween multiple measurements by the same user or measurements bydifferent users. Consequently, the apparatus has an improved interrater/therapist reliability and improved intra rater/therapistreliability compared to prior art devices.

In addition to being able to take accurate measurements which can berepeated by the same or different users, the apparatus are fast and easyto use.

The apparatus are able to measure anatomical angles irrespective of theorientation of the angle which is to be measured. Thus, it does notmatter whether the angle to be measured lies in a horizontal plane, avertical plane, or something in between. Consequently, the apparatus areable to be used to measure an anatomical angle of a person irrespectiveof the position of the person or the part of their body being measured.

The LCDs of the apparatus are sufficiently large to clearly display theangular measurement which is obtained using the apparatus.

The buttons 53 may be used to scroll through and select items from amenu which may be displayed by the LCD 42, The menu items may relate toconfiguring or selecting functions that the apparatus is able toperform. For example, the buttons 53 may be used to put the apparatus into a normal measuring mode where laser beams 83 are emitted by bothlasers 23, the small joint mode discussed earlier, or to select alandmark revision function. The LCD 42 may display instructions for toassist in operating the apparatus.

The housing 51 of the apparatus is preferably made from a material suchas polycarbonate and aluminium for comfort and migration to the user, aswell as for aesthetics and durability of the apparatus.

The battery charger 45 is not limited to being a USB battery charger andmay be any sort of battery charger.

The display 42 may be a touch screen which can be used by a user tooperate the apparatus. For example, the touch screen may display variousoptions related to the operation of the apparatus, and the user mayselect any of those options by appropriately touching the touch screen.

It will be appreciated by those skilled in the art that variations andmodifications to the invention described herein will be apparent withoutdeparting from the spirit and scope thereof. The variations andmodifications as would be apparent to persons skilled in the art aredeemed to fall within the broad scope and ambit of the Invention asherein set forth.

Throughout the specification and claims, unless the context requiresotherwise, the word “comprise” or variations such as “comprises” or“comprising”, will be understood to imply the inclusion of a statedinteger or group of integers but not the exclusion of any other integeror group of integers.

Throughout the specification and claims, unless the context requiresotherwise, the term “substantially” or “about” will be understood to notbe limited to the value for the range qualified by the terms.

It will be clearly understood that, if a prior art publication isreferred to herein, that reference does not constitute an admission thatthe publication forms part of the common general knowledge in the art inAustralia or in any other country.

1. A pocket-sized goniometer having at least a first laser arm and asecond laser arm; the goniometer substantially embodied in a housingprovided with a digital display for display of anatomical angles.
 2. Thegoniometer of claim 1 wherein the goniometer comprises aligning meansfor aligning an axis of the goniometer with anatomical landmarks of thebody, sensing means for sensing an orientation of the axis of thegoniometer while the axis is aligned with the landmarks, and processingmeans for processing the sensed orientation.
 3. The goniometer of claim1, wherein the processing means is able to process a sensed firstorientation of the axis and a sensed second orientation of the axis todetermine an angle between the axis in a sensed first orientation andthe axis in a sensed second orientation.
 4. The goniometer of claim 2,wherein the sensing means includes a tilt sensor for sensing the tilt ofthe axis, and a magnetic sensor for sensing the direction of the axisrelative to a magnetic field.
 5. The goniometer of claim 4, wherein thetilt sensor is able to sense the pitch and roll of the axis.
 6. Thegoniometer of claim 4, wherein the tilt sensor is an accelerometer. 7.The goniometer of claim 4, wherein the magnetic sensor is amagnetometer.
 8. The goniometer of claim 3, wherein the goniometer alsocomprises another aligning means for aligning another axis of thegoniometer with other anatomical landmarks of the body, the aligningmeans are able to be pivoted relative to each other so as to vary anangle between the axes, and the processing means is able to process thesensed orientation to determine the angle between the axes.
 9. Thegoniometer of claim 2, wherein each aligning means is a light source.10. The goniometer of claim 9, wherein the light source is a laser. 11.The goniometer of claim 1, wherein the goniometer also comprises adisplay for displaying the measured angle.
 12. The goniometer of claim1, wherein the goniometer also comprises at least one switch forallowing a user to control the operation of the goniometer.
 13. A methodfor measuring an anatomical angle of a body, the method comprising thesteps of: aligning an axis of a goniometer with anatomical landmarks ofthe body; sensing an orientation of the axis while the axis is alignedwith the landmarks; and processing the sensed orientation to provide adigital display of the angle, and wherein the goniometer comprises atleast a first laser arm and a second laser arm; the goniometersubstantially embodied in a housing provided with a digital display fordisplay of the anatomical angle.
 14. The method of claim 13, wherein thesensing step comprises sensing a first orientation of the axis andsensing a second orientation of the axis; and the processing stepcomprises, processing the first sensed orientation and the second sensedorientation to determine an angle between the axis in the sensed firstorientation and the axis in the sensed second orientation.
 15. Themethod of claim 14, wherein each orientation is sensed by sensing thetilt of the axis and the direction of the axis relative to a magneticfield.
 16. The method of claim 15, wherein the tilt of the axis issensed by sensing the pitch and roll of the axis.
 17. The method ofclaim 13, wherein the method also comprises the step of aligning anotheraxis with other anatomical landmarks of the body by varying an anglebetween the axes, and the processing step comprises processing thesensed orientation to determine the angle between the axes.
 18. Themethod of claim 13, wherein each aligning step comprises aligning alight beam with the landmarks.
 19. The method of claim 18, wherein thelight beam is a laser beam.